Colorectal cancer is one of the most lethal of all cancers. One of the major drivers underlying the development of colorectal tumors is the Wnt/-catenin signaling pathway. We have previously established CRD-BP as a bona fide transcriptional target of Wnt signaling pathway and demonstrated that induction of CRD-BP is responsible for a variety of pleiotropic effects of Wnt/-catenin signaling in human colorectal cancer cells. We have demonstrated that: i) c-myc up-regulation by Wnt/-catenin signaling depends on CRD-BP; ii) CRD-BP facilitates cross-talk between Wnt and NF-?B pathways; iii) CRD-BP mediates activation of GLI1 transcriptional activity in response to Wnt signaling independently of Hh signaling pathway; iv) CRD-BP is transcriptionally regulated by c-myc and is involved in several functions of c-myc proto-oncogene, including regulation on translation, cell size, cell cycle progression, and cell proliferation; v) we have also uncovered a mechanism of CRD-BP-mediated stabilization of TrCP1 mRNA. We hypothesize that CRD-BP plays a central role in the modulation of Wnt/-catenin signaling in the oncogenic transformation of intestinal epithelia, including its role in the maintenance, self-renewal, differentiation, and transformation of intestinal epithelial stem cells (IESCs). We propose to study the mechanisms of CRD-BP involvement in intestinal tumorigenesis. Pursuant to these goals, our specific aims are: 1. To analyze the role of CRD-BP in the regulation of Wnt signaling in CRC cells. 2. To elucidate the mechanisms of CRD-BP function in intestinal tumorigenesis. Overall, the completion of the proposed studies will help elucidate the role of CRD-BP in colorectal carcinogenesis. It will also delineate the mechanisms of regulation and function of CRD-BP in these tumors. These studies may potentially lead to the design of agents capable of inhibiting CRD-BP that might be utilized in the therapy of CRC.